Question

How can I display a sort arrow in the header of the sorted column in a list view which follows the native look of the operating system?

Answer 1

You can use the following extension method to set the sort arrow to a particular column:

[EditorBrowsable(EditorBrowsableState.Never)] public static class ListViewExtensions {     [StructLayout(LayoutKind.Sequential)]     public struct HDITEM     {         public Mask mask;         public int cxy;         [MarshalAs(UnmanagedType.LPTStr)] public string pszText;         public IntPtr hbm;         public int cchTextMax;         public Format fmt;         public IntPtr lParam;         // _WIN32_IE >= 0x0300          public int iImage;         public int iOrder;         // _WIN32_IE >= 0x0500         public uint type;         public IntPtr pvFilter;         // _WIN32_WINNT >= 0x0600         public uint state;          [Flags]         public enum Mask         {             Format = 0x4,       // HDI_FORMAT         };          [Flags]         public enum Format         {             SortDown = 0x200,   // HDF_SORTDOWN             SortUp = 0x400,     // HDF_SORTUP         };     };      public const int LVM_FIRST = 0x1000;     public const int LVM_GETHEADER = LVM_FIRST + 31;      public const int HDM_FIRST = 0x1200;     public const int HDM_GETITEM = HDM_FIRST + 11;     public const int HDM_SETITEM = HDM_FIRST + 12;      [DllImport('user32.dll', CharSet = CharSet.Auto, SetLastError = true)]     public static extern IntPtr SendMessage(IntPtr hWnd, UInt32 msg, IntPtr wParam, IntPtr lParam);      [DllImport('user32.dll', CharSet = CharSet.Auto, SetLastError = true)]     public static extern IntPtr SendMessage(IntPtr hWnd, UInt32 msg, IntPtr wParam, ref HDITEM lParam);      public static void SetSortIcon(this ListView listViewControl, int columnIndex, SortOrder order)     {         IntPtr columnHeader = SendMessage(listViewControl.Handle, LVM_GETHEADER, IntPtr.Zero, IntPtr.Zero);         for (int columnNumber = 0; columnNumber <= listViewControl.Columns.Count - 1; columnNumber++)         {             var columnPtr = new IntPtr(columnNumber);             var item = new HDITEM                 {                     mask = HDITEM.Mask.Format                 };              if (SendMessage(columnHeader, HDM_GETITEM, columnPtr, ref item) == IntPtr.Zero)             {                 throw new Win32Exception();             }              if (order != SortOrder.None && columnNumber == columnIndex)             {                 switch (order)                 {                     case SortOrder.Ascending:                         item.fmt &= ~HDITEM.Format.SortDown;                         item.fmt |= HDITEM.Format.SortUp;                         break;                     case SortOrder.Descending:                         item.fmt &= ~HDITEM.Format.SortUp;                         item.fmt |= HDITEM.Format.SortDown;                         break;                 }             }             else             {                 item.fmt &= ~HDITEM.Format.SortDown & ~HDITEM.Format.SortUp;             }              if (SendMessage(columnHeader, HDM_SETITEM, columnPtr, ref item) == IntPtr.Zero)             {                 throw new Win32Exception();             }         }     } } 

Then, you can call the extension method like such:

myListView.SetSortIcon(0, SortOrder.Ascending); 

It works by using P/Invoke to:

• Get the handle to the header control for a list view using the LVM_GETHEADER message.
• Get the information about a header column using the HDM_GETITEM message.
• It then modifies the fmt to set / clear the HDF_SORTDOWN and HDF_SORTUP flags on the returned HDITEM structure.
• Finally it re-sets the information usintg the HDM_SETITEM message.

This is what it looks like: